Tehran and Six World Powers Still Deadlocked Over Major Issues, but Dialogue Stays Alive

VIENNA—Iran agreed to new steps to contain its nuclear work in exchange for additional sanctions relief from the U.S. as the two sides extended negotiations for four more months to reach a comprehensive deal.

Under Friday's deal, the U.S. will give Tehran access over the next four months to an additional $2.8 billion in oil export revenues frozen abroad by American sanctions, Secretary of State John Kerry said.